What is a Transmission Shift Solenoid? | Symptoms of a bad Transmission Solenoid

Modern automatic transmissions use pressurized hydraulic fluid to change gears. Whenever a gear change is required, the car’s computer activates a transmission solenoid, which directs transmission fluid into the valve body to engage the correct gear. If one of these electromechanical valves fails, then all sorts of transmission problems can ensue. This article explains the transmission control solenoid working, symptoms, and causes.

What Is a Transmission Solenoid?

The transmission solenoid is a type of electromechanical valve that controls fluid flow into and throughout an automatic transmissionSolenoids can be normally open or normally closed. They operate via a voltage or current supplied by the transmission computer or controller

Transmission Solenoid

In modern transmissions, the transmission solenoid generally comes in a pack that is installed in the transmission control unit, the transmission control module, or a transmission valve body.

Transmission fluid is critical to the function of the transmission. Your transmission cannot operate properly if its flow is impeded or hindered.

Working of Transmission Solenoid

Transmission solenoids are powered by an electrical current supplied by the transmission controller or computer.

Working of Transmission Solenoid

The speed sensors within your car’s engine constantly monitor how your car is running and analyse what needs to be adjusted. The speed sensors work with the ECU or TCM to send signals to parts of your car when changes need to be made, including telling transmission solenoids when to open or close so that your car can change gears.

The transmission computer sends instructions to the individual transmission solenoids in the pack, which then direct transmission fluid to specific clutch packs or servo valves to control gear shifting to suit the given driving conditions and engine requirements.

A transmission solenoid generally consists of nine parts that must work together for your transmission to operate properly.

Bad Transmission Solenoid Symptoms

A bad transmission solenoid generates one of the below-given symptoms:

  1. Check Engine light
  2. Unusual gear shifts
  3. Skipping Gears
  4. Transmission Warning Light
  5. Unable to downshift
  6. Limp mode
  7. Stuck in gear
  8. Shifting delays
  9. Engine continues to rev when applying the brakes

1) Check Engine Light

The check engine light illumination is one of the first signs of a bad transmission solenoid.  The check engine light will light up even when there is a problem with the transmission.

Mostly it lightens up, and you will see a P0776 Trouble code. This code basically tells you that there is a problem with the transmission control, and more trouble codes will be found in the transmission control module.

Read More: Causes of Check Engine Light Blinking

2) Unusual Gear Shifts

The unusual gear shifting is one of the most common symptoms of a bad transmission solenoid. 

For instance, when you’re driving with a specific gear and the vehicle suddenly makes an unexpected shift to a higher gear, this can also be dangerous for the driver and the vehicle.

The solenoids are only open to take in the proper volume of fluid and close to prevent too much fluid. However, a bad transmission solenoid fuse or faulty wiring in the solenoid can make your vehicle make an unexpected gear shift.

This problem manifests either. This means you may experience an unexpected shifting to a higher gear, thereby increasing the vehicle speed. The gear may also shift to a lower one when you’re trying to accelerate or get past a slower vehicle.

3) Skipping Gears

If your vehicle has problems engaging certain gears and tends to skip over the “problem gear” whenever you attempt it, there’s a good chance that a specific solenoid is broken or worn out.

4) Transmission Warning Light

Some cars do also have a separate transmission warning light. If this light is on, it might be a stored trouble code related to a bad transmission shift solenoid.

To read the trouble codes from the transmission control module, you need an OBD2 scanner to read generic and enhanced trouble codes. Most cheaper ones can only read the codes from the engine control module.

5) Unable to downshift

Sometimes, a problem with a vehicle solenoid may not affect acceleration and gear upshifting, but then you will experience difficulty in downshifting – either slow downshifting or vehicle not downshifting at all.

This happens when your vehicle’s transmission solenoid becomes faulty and stuck open. There could be several reasons for this.

First, it can be a problem with the internal wiring of the solenoid. Bad wiring within the solenoid may not transmit electrical signals to the solenoid, causing it to stay open, take in more fluids and pressure, and be unable to downshift.

Another reason is simply a damaged solenoid. When the solenoid itself is damaged, you will experience downshifting difficulties like this. Your vehicle may also be unresponsiveness to downshifting due to the intake of dirty fluid.

6) Limp Mode

In response to solenoid failures, some vehicles engage limp mode, a protective function for your engine that caps RPM at 2500-3000, limits shifting, and keeps you under third gear. If your vehicle has engaged in this protective mode, you’re probably dealing with a solenoid issue.

Read More: Limp Mode Symptoms and Causes

7) Stuck in Gear

If the shift solenoid got damaged while the gear was engaged, it might cause the transmission to be stuck in that gear. If this is the case, you can either try to give the shift solenoid external power to release the gear if you know how to do it.

Read More: Symptoms of bad Gearbox

8) Shifting Delays

If the transmission control unit recognizes any shift solenoid problems, it may cause the transmission to shift very slowly. This applies to both upshifting and downshifting.

9) Engine continues to rev when applying the brakes

If your tachometer needle keeps climbing as you hit the brakes, there’s a good chance you have a faulty solenoid.

Transmission Shift Solenoid Location

The transmission solenoid is most commonly located in an assembly called Valve Body. In most cases, you will need to remove the whole valve body to be able to have access to the solenoids. 

Transmission Solenoid Replacement Cost

The replacement cost of a transmission solenoid depends greatly on your car model and transmission model.

A single-shift solenoid’s replacement cost is between $90 and $360, and a shift solenoid pack costs between $390 and $710, including transmission fluid, filter, parts, and labor work.

These are the prices, including parts and labor costs. The prices do not include diagnosis and fluid replacement costs.

  • Valve body replacement cost: $490 to $1100
  • Shift solenoid pack replacement cost: $290 to 610$
  • Single shift solenoid replacement cost: $40 to 160$

Common Shift Solenoid Trouble Codes

  • P0774 – Shift Solenoid E – Intermittent fault
  • P0773 – Shift Solenoid E – Electrical
  • P0750 – Shift Solenoid A
  • P0772 – Shift Solenoid E – Stuck Solenoid @ ON
  • P0771 – Shift Solenoid E – Performance or Stuck Off
  • P0770 – Shift Solenoid E
  • P0769 – Shift Solenoid D – Interm
  • P0768 – Shift Solenoid D – Electrical
  • P0767 – Shift Solenoid D – Stuck Solenoid @ ON
  • P0766 – Shift Solenoid D – Performance or Stuck Off
  • P0765 – Shift Solenoid D
  • P0764 – Shift Solenoid C – Intermittent fault
  • P0763 – Shift Solenoid C – Electrical
  • P0762 – Shift Solenoid C – Stuck Solenoid @ ON
  • P0761 – Shift Solenoid C – Performance or Stuck Off
  • P0760 – Shift Solenoid C
  • P0759 – Shift Solenoid B – Intermittent fault
  • P0758 – Shift Solenoid B – Electrical
  • P0757 – Shift Solenoid B – Stuck Solenoid @ ON
  • P0756 – AW4 Shift Sol B (2-3) – Functional Failure
  • P0755 – Shift Solenoid B
  • P0754 – Shift Solenoid A – Intermittent fault
  • P0753 – Transmission 3-4 Shift Solenoid – Relay Circuits
  • P0752 – Shift Solenoid A – Stuck Solenoid @ ON

Diagnosis and fixing of a Bad Transmission Solenoid

To diagnose the problem of the transmission solenoid, we have to find out what is causing the problem and which part of the engine it’s coming from, as it may be a problem with the internal wiring, transmission control module, or some other mechanical fault.

If the trouble code tells us that it’s stuck or an electrical problem, it is most likely a wiring or shift solenoid problem.

Many shift solenoid-related codes can be solved by doing a transmission fluid replacement or carrying out a transmission flush. A transmission fluid change is often not that expensive and worth doing.

Follow the below-given steps to scan a bad transmission solenoid:

  1. Find a transmission wiring diagram for your transmission.
  2. Find out which pins are going to the affected shift solenoid.
  3. Loosen the transmission wiring plug on the transmission
  4. Use the OBD2 scanner and start the affected shift solenoid output test.
  5. Measure with a multimeter to see whether you get both 12 volts and ground to the shift solenoid at the plug on the transmission on the affected pin.
  6. If you do not get both 12 volts and ground – you may have a wiring problem or a faulty TCM (transmission control unit).

FAQ Section

Can you drive with a bad transmission shift solenoid?

Yes, you can drive a vehicle with a bad transmission solenoid. Nevertheless, you should keep in mind that the problem may escalate into an expensive repair if not taken care of as soon as possible.

Also, since solenoids are in charge of controlling gear shifting and vehicle acceleration, the driver will experience difficulty as he drives without fixing the solenoid fault.

What does a Transmission Solenoid look like?

The solenoid body is generally made of steel, and it has a cylindrical shape. Transmission solenoids have a valve and return spring in them. The solenoid coil consists of wire wound around a conductive component that acts as an electronic magnet—controlling the valve’s position. 

Can you start a car with a bad solenoid?

Unless your vehicle has a bad starter solenoid, you can still start your car. Faulty starter solenoids affect a vehicle by causing it to start on its own without the driver turning the key to start the vehicle.

Whether your vehicle is having a problem with the starter solenoid or the transmission solenoid, you should address the problem without delay.

How do you fix a stuck shift solenoid?

In some cases, you can fix a stuck shift solenoid by changing the transmission oil and filter and doing a transmission fluid flush. Unfortunately, in most cases, you will need to replace the stuck shift solenoid if a flush doesn’t help.

How long does it take to change a transmission solenoid?

Changing a transmission solenoid takes about 2 to 4 hours, which makes it easier to calculate the labor cost for fixing this part of your vehicle. So far, you’re paying per hour; you can deduce what the total cost will be by adding the cost of hours it’ll take to the cost of the part replacement.

How many shift solenoids are in a transmission?

There are usually 2 to 5 shift solenoids in most automatic transmissions, depending on the make and model of the car. Their primary purpose is to control the flow of hydraulic fluid to the clutch packs in the transmission, which allow for shifts between gears.

What causes the Transmission Shift Solenoid to go bad?

  1. Faulty Solenoid Wiring
  2. Dirty Transmission Fluid
  3. Slipping Transmission
  4. Wear & Tear

Can a clogged transmission filter cause shift problems?

Clogged filters will make it hard to switch gears. If your car isn’t shifting smoothly, or if it hesitates or slips when you try to shift, you could have any number of transmission problems, so it’s best to have a professional look at it.

What causes a transmission to not shift?

Over time, dirt, debris, and other tiny particles can accumulate in the transmission fluid, affecting its fluid properties. This can cause the vehicle to die when you shift into drive or reverse, allow a loss of power, transmission slip, rough shifts, or even prevent the vehicle from shifting into gear at all.

How do you know if you need a new transmission solenoid?

Plenty of transmission shifting problems can be traced back to a malfunctioning shift solenoid, including:

  1. Check Engine light
  2. Shifting delays
  3. Stuck in gear
  4. Unusual gear shifts
  5. Limp mode
  6. Skipping Gears
  7. Unable to downshift
  8. Transmission Warning Light
  9. Engine continues to rev when applying the brakes

Leave a Comment